Renal and Urinary systems

Question 1

three functions of the nephron

Answer 1

1) filtration
2) tubular reabsorption
3) tubular secretion

Question 2

afferent arteriole

Answer 2

carries blood to glomerulus

Question 3

efferent

Answer 3

a tuft of capillaries that filters a protein-free plasma into tubular component

Question 4

Bowmann’s capsule

Answer 4

collect the glomerular filtrate

Question 5

proximal & distal tubules

Answer 5

uncontrolled reabsorption & secretion of selective substances occur here

Question 6

descending loop of henle

Answer 6

reabsorption water

Question 7

collecting duct

Answer 7

receives fluid from DCTs of several nephrons as it passes b/c into medulla

Question 8

fluid travel through the nephron

Answer 8

renal artery -> afferent arteriole -> glomerulus -> efferent =» cortical nephron & juxtamedullary nephron

glomerulus -> Bowman’s capsule -> proximal tubule -> descending of henle -> thick, ascending loop -> distal convoluted tubule -> collecting duct -> ureters -> bladder

Question 9

juxtamedullary (abundance, vasculature, location)

Answer 9

15-20% of all nephrons; very long nephron loops, efferent arterioles branch into vasa recta and long nephron; inner part of kidney called medulla

Question 10

cortical nephron

Answer 10

most abundant; efferent arterioles branch into peritubular capillaries around PCT and DCT; within renal cortex, tip dips into renal cortex

Question 11

factors governing glomerular filtration rate (GFP)

Answer 11

1) surface area of membrane
2) permeability of membrane
3) net filtration pressure

Question 12

functions of urinary system

Answer 12

regulates

• water balance
• quantity of ECF ions
• plasma volue
• A/B balance
• osmolarity
• metabolic wastes excretion
• foreign waster excretion
• erythropoietin and renin secretion
• vitamin D to active form

Question 13

nephron

Answer 13

• structural and functional unit of the kidney

- consists of glomerulus and renal tubules, and associated blood vessels

Question 14

subdivisions of tubule

Answer 14

• Bowman’s capsule
• proximal convoluted tubule
• loop of Henle
• distal convoluted tubule

Question 15

cortical nephrons

Answer 15

• most abundant
• almost entirely in cortex
• only small part of LOOP of henle extends to medulla

Question 16

juxtamedullary nephrons

Answer 16

• 15-20% of all nephrons
• @ cortex-medulla junction
• loop of henle extends deep into medulla
• have unique, straight vessels called the vase recta

Question 17

What establishes the medullary osmotic gradient?

Answer 17

cortical and juxtamedullary nephrons

Question 18

Kidneys also…(2 things)

Answer 18

• perform gluconeogenesis during prolonged fasting

- are also endocrine glands

Question 19

glomerular filtrate

Answer 19

fluid collected in capsular space

Question 20

hematuria

Answer 20

• damage to filtration membrane

- presence of blood cells in glomerular filtrate

Question 21

proteinuria

Answer 21

• damage to filtration membrane

- increased presence of protein in urine

Question 22

Forces regulating NFP

Answer 22

Outward
1. hydrostatic blood pressure (55 mmHg)
- bigg diameter of afferent and small diam of efferent
Inward
1. blood colloid osmotic pressure (30 mmHg)
2. capsular hydrostatic pressure

Question 23

glomerular filtration rate

Answer 23

total amount of filtrate formed by the kidneys per minute (125 mL/ min)

Question 24

What happens during exercise in terms of autoregulating the GFR?

Answer 24

• Blood pressure increases

- Afferent arteriole CONSTRICTS to maintain GFR, otherwise risk dehydration

Question 25

What happens during relaxation in terms of autoregulating the GFR?

Answer 25

• Systemic pressure decrease

- Afferent arteriole DILATES to maintain GFR, otherwise not enough filtration

Question 26

Filtration membrane is composed of 3 layers

Answer 26

1) Fenestrated glomerular endothelium
2) Basement membrane
3) Filtration slits
- Permits free passage of most substances less than plasma proteins

Question 27

Myogenic mechanism

Answer 27

• Vascular smooth muscle cells contract when stretched (high BP), reducing blood flow
• Vascular smooth muscle cells relax and dilate when not stretched (low BP), increasing blood flow

(weightlifter, the pressure, in vessel wall)

Question 28

What are the mechanisms that regulate (help to maintain) glomerular blood pressure?

Answer 28

Kidney has 2 autoregulatory mechanisms

1. myogenic mechanism
2. tubuloglomerular feedback mechanism

Question 29

What happens in tubuloglomerular mechanism, when there is a high osmolarity vs. a low osmolarity?

Answer 29

1) High osmolarity (great concentration of ions, high filtrate flow rate) in terminal portion of ascending loop of Henle, reduced absorption (too high GFR)
- Macula densa cells release chemicals that cause vasoconstriction, that constrict afferent arteriole
- GFR decreases
- Tubular filtrate flow slows
- Reabsorption of sodium and chloride ions increases

2) Low osmolarity (low bp and GFR)
In response to low osmolarity, the macula densa cells
- Release less vasoconstrictor
- Signal the JG cells to release renin, JG cells can also sense the very low bp and rel. renin in response

Question 30

Glycosuria

Answer 30

Abnormal urinary constituent: glucose
Nonpathological: excessive intake of sugary foods
Pathological: diabetes mellitus

Question 31

Proteinuria

Answer 31

Abnormal urinary constituent: protein
Nonpathological: excessive physical exertion; pregnancy; high-protein diet
Pathological (over 250 mg/day); heart failure, severe hypertension, glomerulonephritis; often initial sign of asymptomatic renal disease